@vaartis Maybe I can help, what do you mean by jaggy?
Line renderer is fine for me.
Here's a circle using a line renderer in local space.
And some other shapes too.
(Ignore the project in the background)
@vaartis Wait... why are you looking at a ticket from 2018?
What version of Unity are you using?
@vaartis There's also the Visual Effect component that is similar to a particle system, but runs on the GPU (if memory serves).
I don't have much hands-on experience with it though.
And good luck with whatever you're making.